7. PROJECT SUMMARY/ABSTRACT Adolescent alcohol use (AU) is of great public health interest because it is associated with acute and long-term negative outcomes such as risky sexual behaviors, illicit drug use, problematic AU later in life, and death. Understanding how adolescents navigate peer contexts is critical to prevention efforts because adolescent AU typically occurs with peers. Social development models posit that interactions between adolescent social goals and parenting style influence how adolescents transact with their social environments, and may protect adolescents from peer contexts that promote AU. A growing body of work suggests that an interpersonal style characterized by valuing and establishing close interpersonal relationships (high communion), while simultaneously being able to articulate opinions to peers (high agency), helps adolescents achieve important developmental milestones (e.g., forming close friendships and independence) while also avoiding engagement in AU. Responsive and demanding parenting is thought to help foster this protective interpersonal style, and successful peer relationships and avoidance of AU involves developmentally appropriate shifts in parenting and social goals. Although it has been repeatedly asserted that social goals and parenting styles operate jointly to curtail the initiation and escalation of adolescent AU in adolescence, and show developmental changes, no work to our knowledge has considered the dynamic interplay between agency, communion, and parental responsiveness and demandingness in the etiology of adolescent AU. This is a notable gap because understanding the joint effects of these adolescent and parenting characteristics may inform potential targets for preventive interventions aimed at mitigating negative peer influences and helping adolescents achieve important developmental tasks of intimacy and autonomy. The proposed study will address this gap in the literature. We propose to (1) identify patterns of adolescent social goals and parenting style using latent profile analysis, (2) evaluate developmental changes in social goals and parenting using latent transition analysis, and (3) examine how these transitions relate to the initiation and escalation of AU from middle to late adolescence as well as DSM 5 Alcohol Use Disorder symptoms in late adolescence. A community sample of 387 families (target child and caregiver) was assessed annually for 7 assessments (91% retention). Adolescents completed measures of parenting and interpersonal goals during the first 3 assessments and they completed measures of AU at all 7 assessments. Results will advance our understanding of how youth adapt to a social context in which risk behavior becomes increasingly common with age, and may provide important intervention opportunities for promoting positive adaptation during adolescence.